I think you are misinterpreting that line as being the literally true expectation of the author, rather than the author saying what they have to say to minimize

I think you are misinterpreting that line as being the literally true expectation of the author, rather than the author saying what they have to say to minimize repeating of the prompt, which is not really useful output. Just because that line reads as a person being adamant does not mean that the author really truly believes that the prompt MUST not be repeated and any leak is a security incident. It could just be that the bot has a tendency to talk about itself unless instructed not to, and that's part of the instruction.